The invention relates to a process for the production of a low-loss optical waveguide in an epitaxial silicon film of a silicon structural element with integrated electronic components in a silicon substrate.
Such a method is described in "Optics Letters," Vol. 13, No. 2, 1988, pages 175 to 177. In this known method for the production of an optical waveguide in an epitaxial silicon film of a silicon structural element, an insulating layer of SiO.sub.2 or Al.sub.2 O.sub.3 is provided between the silicon substrate and the epitaxial silicon film; the epitaxial film is formed of a "silicon-on-insulator" (SOI) material. The optical waveguide is made complete by the fact that in the known method, a so-called rib waveguide is formed by etching, as described in detail in "IEEE Journal of Quantum Electronics," Vol. QE-22, No. 10, 1986, pages 873 to 879. Lateral waveguiding is achieved in this manner. An advantage of an optical waveguide produced in this way is that interactions between an electrical field and an optical field are possible by means of charge carrier injections. In addition, the waveguide is very low-loss, in advantageous manner, because its attenuation is less than 1 dB/cm. However, there are difficulties in the production of such an optical waveguide, in that the SOI material, which is rather rare until now, must be used to produce it.